1. Field of the Invention
The present invention relates to a system for use in the preparation of autologous or single-donor fibrin sealant. The invention further relates to a method of preparing fibrin sealant.
2. Background Information
The blood coagulation system is a complex series of proteins and factors which are activated sequentially to produce an insoluble fibrin mass or clot. In the final stages of the process, fibrinogen is cleaved by thrombin to generate fibrin monomer, which rapidly polymerizes and is crosslinked by activated Factor XIII to form an insoluble matrix.
Preparations of human coagulation factors including fibrinogen and thrombin, have been used extensively in surgery over the last ten years [Schlag G. and Redl (eds) Fibrin Sealant in Operative Medicine - Thoracic-Cardiovascular Surgery, vol. 1-7 Springer-Verlag, Heidelberg]. These biological fibrin sealants promote hemostasis and wound healing by sealing leakage from tissues, sutures, staples, and prostheses and are particularly useful during open heart surgery in heparinized patients. The sealants also have limited use as an adhesive for the bonding of tissues and they reduce the amount of blood required for transfusions by controlling intraoperative bleeding. Their effectiveness is reflected in the extensive range of surgical applications for which they have been used, including cardiovascular surgery, plastic surgery, orthopedics, urology, obstetrics and gynecology, dentistry, maxillofacial and opthalmic surgery.
Fibrin sealant products prepared from pooled human plasma are available commercially in Europe (Tissucol/Tisseel, Immuno AG, Vienna, Austria and Beriplast P, Hoechst, West Germany) but have not received U.S. Food and Drug Administration approval, probably due to possible risk of transmission of HIV-1, hepatitis B and other serologically transmitted illnesses.
As an alternative, some hospit.las are preparing fibrin sealant in-house using the patient's own blood (autologous) or single-donor (homologous) plasma as a source of fibrinogen and Factor XIII. The components are typically prepared by freezing plasma at temperatures below -20.degree. C. overnight, slowly thawing the material at 0-4.degree. C., centrifuging, and transferring the cryoprecipitate to a syringe or spray container [Dresdale et al Ann. Thorac. Surg. 40:385(1985); U.S.Pat. No. 4,627,879]. The procedure usually requires several hours, making the product unavailable for emergency cases. The lengthy manipulations currently required to generate fibrin sealant also introduce the risk of contaminating the product and transmitting viral infections to the technician(s) involved.
The thrombin, usually purified from bovine plasma, can be obtained commercially and is typically prepared in a separate syringe or spray container. The two solutions are delivered simultaneously or alternately to generate fibrin sealant at the site of the wound or, alternatively, the sealant is applied to a collagen matrix (e.g. Gelfoam or Avitene) and then pressed against the site [Lupinetti et al. J. Thorac. Cardovasc. Surg. 90:502 (1985); and U.S. Pat. 4,453,939].
SUMMARY OF THE INVENTION
It is a general object of the present invention to provide a system and method for the rapid preparation of autologous fibrin sealant which removes the risk of transmitting infection (especially HIV-1 and hepatitis infections) since the fibrin sealant is made from the patient's own blood components. The system can also be used to prepare fibrin sealant from designated single donors. In addition, the system and method can be used to prepare fibrin sealant from single-donor animals or pooled animal plasma for use in veterinary applications. It is another object of the present invention to provide a system and a method for the preparation of fibrin sealant in high yield with minimal risk of exposure to the technician and minimal risk of contaminating the blood products.
These and other objects are realized in accordance with the present invention by obtaining blood coagulation or clotting factors from a patient's own blood or from an appropriate donor by use of a system that includes two or more sterile containers connected by sterilized tubing or a single container having two or more compartments defined therewithin. The patient or donor's blood is drawn into one container or compartment of the system. One or more anti-coagulants are present within the first container or compartment and the blood is mixed therewith. The container is then subjected to, for example, centrifugation so as to separate the plasma from red blood cells. The plasma is transferred from the first container or compartment into a second container or compartment of the system. An agent that effects precipitation of the blood coagulation factor(s) is contained within the second container and is mixed with the plasma. The mixture is then subjected to, for example, centrifugation to obtain a coagulation factor-enriched precipitate. The precipitate is retrieved from the second container or compartment and is mixed with a solution of thrombin and calcium to prepare the fibrin sealant. In the alternative, the factor-poor plasma is decanted from the second container or compartment. The precipitate can then be dissolved in a buffer and transferred to a delivery device. Thrombin and, if necessary calcium, are mixed with the fibrinogen/Factor XIII solution to form the fibrin sealant.
Other objects, features and characteristics of the present invention, as well as the methods of operation and functions of the related elements of the structure, and the combination of parts and economies of manufacture, will become more apparent upon consideration of the following detailed description and the appended claims, with reference to the accompanying drawings, all of which form a part of this specification, wherein like reference numerals designate corresponding parts in the various figures.